Gate reset circuit



Dec. 9, 1958 E: ADAMS 2,864,034

GATE RESET CIRCUIT Filed Jan. 11, 1957 INVENTOR. JOHN E. ADAMS ATTORNEYS 2,864,034 Patented Dec. 9, 195g tie GATE RESET CIRCUIT John E. Adams, Newtonville, Mass, assignor to Sylvania Electric Products Inc., Salem, Mass., a corporation of Massachusetts Application January 11, 1957, Serial No. 633,590

Claims. (Cl. 315-846) This invention relates in general to electronic counting devices and more particularly to glow discharge counting tubes and drive circuits for such tubes.

In recent years, many devices and circuits have been developed for counting. One of the most popular and most widely accepted types of counting device has as its primary component, a gas filled glow discharge transfer counting tube. Tubes of this type are multi-element tubes which usually contain a single ring anode surrounded by a large number of cathodes. Under operating conditions, a glow discharge is formed in the area of the cathode to which current is flowing from the anode. Counting is indicated by the transfer of that glow discharge from one cathode to the next. To accomplish this transfer of the glow discharge from cathode to cathode, it has proven necessary in some tubes to utilize so-called guides or guide electrodes between neighboring cathodes. Drive circuits have been developed which cause the glow discharge to transfer via the intervening guides from one cathode to the next in response to a single signal usually of the pulse type.

Certain applications for counting and indexing have arisen wherein it is desired that counting action take place only during predetermined periods and only to a certain predetermined quantity. To accomplish this in a glow-discharge transfer apparatus, it is necessary that the glow discharge in a tube, or series of tubes, be held immovable at some zero position on a given cathode until an enabling or initiating pulse is received. The further limitation of ending the count at a predetermined quantity which has been imposed requires that the glow discharge, after reaching a chosen final cathode, be returned to the initial or zero cathode position. In other words, it has proven desirable to provide a tube or tubes which will run through a certain predetermined count only after a suitable gating signal has been given and return to the starting position, that is, be re-set. The counting will start again only after receipt of another suitable count-initiating or gating signal regardless of interruptions in the pulses being counted or occurence of pulses after the preset final count has been reached.

A circuit for providing this type of action might properly be called a gate-reset circuit. No simple electronic counters capable of performing this function have been available. Some extremely complex apparatus has been devised for similar functions, but the complicated structure and high cost of that apparatus has prevented its 1 circuit and glow-discharge transfer counting tube operable in response to input pulses received under certain conditions. To achieve the objective of counting only to a predetermined value and only after receipt of a count-initiating pulse, a bistable circuit is provided. The bistable circuit is of the multivibrator type and is triggered from one condition of operation to the other by the initiating pulse. The bistable circuit is returned to its original condition of operation automatically by the input pulses to be counted after the predetermined count of input pulses is made.

More specifically, an initiating pulse applied to the bistable circuit permits counting of input pulses by the counting tube to begin. The first input pulse to be counted is then enabled to release the glow discharge from the zero cathode and to transfer it to the next adjacent cathode. Subsequent pulses cause the transfer of the glow discharge from cathode to cathode and the counting action continues until a predetermined final cathode is reached by the glow discharge in the counting tube. The next input pulse causes the bistable circuit to reverse its condition of operation. The reversal is effective to drive the zero cathode to a potential sufficiently negative that the glow discharge is returned to invest that cathode. Now, however, before the glow discharge can transfer to an adjacent cathode and recommence the cycle of transfer, an initiating pulse must again reverse the condition of operation of the bistable circuit. For a better understanding of the present invention, together with other objects, features and advantages, reference should be made to the following detailed description of a preferred embodiment and the accompanying drawing, the single figure of which is a schematic diagram of one embodiment of the circuit and tube of the present invention.

The gas filled glow transfer counting tube 10 is shown only fragmentarily in the drawing. A practical tube for use in the invention might, for example, be a Sylvania Type No. 6476. In that tube there is an anode surrounded by slim rod-like cathodic elements arranged in an annular row. Each third cathodic electrode is usually designated as a main or count-indicating cathode. Between each main cathode and its neighboring main cathodes are two guide electrodes. All guide electrodes lying adjacent main cathodes in the clockwise sense are electrically connected together and all guide electrodes lying adjacent main cathodes in'the counter-clockwise sense are tied together electrically. These connections are usually internal of the tube, although they need not be. With the exception of the zero and final cathodes, all of the main cathodes of the counting tube are also electrically connected together. These details have been eliminated in the drawing to permit easier visualization of the essence of the present invention.

A first source of potential 21 which may be of the 6B0 voits D. C. is connected through an anode resistor 23 to the anode 11 of counting tube 10. The guide electrodes which include guide electrode 13 are connected through a parallel combination of a resistor 25 and a condenser 27 to the anode of a triode amplifier 37. The guide electrodes which include guide 14 are connected to the junction of a resistor 29 and a condencer 31. Condenser 31 is connected back to ground and resistor 29 is connected to the anode of triode 37.

Input signals to be counted are applied through a conventional coupling condenser 33 and a resistor 35 to the grid of the triode amplifier 37. A source of negative voltage 38 which may be of the order of -9 volts is also connected to the grid of triode 37 through a grid resistor 39. Leads are brought out separately from any two of the main cathodes of counter tube 10, the other main cathodes (not shown) being bussed together and having a separate lead. One of these two cathodes 12a is chosen as the originating or zero cathode. The other of these cathodes 12b, is chosen to be the terminating or final cathode. Any one 0f the mam cathodes may be selected as the zero cathode, and any one of them may be' selected as the final cathode. If it is considered desirable, suitable selector switches can be provided in the circuit so that either or both the zero and final cathode functions can be switched to any of the cathodes.

In the illustrated circuit, however, the zero cathode 12a is connected to a load resistor 41 and to the anode resistor 46 of the second section 4% of a duo-triode 49. The opposite end of load resistor 41 is tied to a second source of positive potential 43, which may be of the order of200 voltsD. C., and it is also connected to the anode resistor 45 of the first section 49a of the duotriode 49.

Connected to the terminating or final cathode 12b is a suitable load resistor 51. The other end of resistor 51 is connected with the other end of resistor 41 to the second source of positive voltage 43. Cathode 12b is also connected through a resistor 47 and a condenser 48 to the grid of triode section 49a. The cathodes of the two triode sections of duo-triode 49 are con-- nected together and are grounded through a cathode resistor 57. An input circuit designated by the terminal 54 is provided for the grid of the triode section 49a anda similar circuit is designated by terminal 56 for the grid of triode section 4912. A grid resistor 61 is connected to the grid of triode section 49a and leads to a source of negative potential 63 of the order of 9 volts. The grid of triode section 49b is similarly connected to the source of negative potential 63 through a grid resistor 65. A feed-back connection is established between the anode of triode section 49b and the grid of triode section 49a by means of the resistor 67. Another feed-back circuit is established between the anode of triode section 49a and the grid of triode section 49b by means'of a resistor 69 connected therebetween. An output terminal 70 is provided at the anode of triode section 49b.

Typical values of components of the circuit are as follows: Resistor 23, 510 kilohms; resistors 25 and 29, -l50 kilohms; resistor 35, 3 megohms; resistor 39, 300

-kilohms; resistor 47, 2.2 megohms; resistor 45, 150 kilohms; resistor 46, 20 kilohms; resistor 57, 2 kilohms, resistors 61'and 65,2.2 megohms; resistors 67 and 69, 20 megohms; resistors 41 and 51, 62 kilohms. Condenser 33may be of IOOO-micro-microfarads; condensers 27 and 31, 470 micro-microfarads; condenser 48, 47 micromicrofarads. The triodes used may be Sylvania Type 12AT7 and' a suitable counting tube would be Sylvania Type 6476.

It maybe assumed as a starting point in explaining the operation of the invention that no count-initiating pulse has yet arrived at the duo-triode 49, and that at this time, triode section 4% is conducting,'section 49a is cut-off, and the glow discharge is investing the zero cathode 12a. These conditions are maintained prior to the occurrence of a count-initiating pulse due to the 'brstable nature of the multivibrator circuit in conjunction wlth the circuit elements as more fully explained below.

An initiating pulse which may be positive if it is applied through the terminal 54 to the grid of triode 49a, or which may be negative if applied through terminal 56 to the grid of section 4%, reverses the condition of operation of the bistable circuit. The reversal of condition of operation takes placein a manner which is conventional in multi-vibrator circuits, and will be explained only briefly. Considering first a negative pulse applied to the grid input terminal 56 of triode section 49bythe'sudden driving of that grid negative, causes "the section'49b-to be cutofi. The cut-off of current flow in 'triode se'ction'49b causes the'voltage at the anode of sec- 4 tion 4% to rise suddenly. This positive-going voltage at the anode of 'trio'de section 49b is coupled directly through the feed-back resistor 67 to the grid of triode section 49a. The positive-going voltage at the grid of triode section 49a causes that section of the tube to commence conduction. It is clear that a positive pulse applied to the input grid terminal 54 of triode section 49a would accomplish the same result. In this case, however, the sudden raising of the voltage on the grid of triode section 49a would cause conduction in that section. With the increase in conduction of triode section 49a, the voltage at the anode of triode section 49a drops to a lower value. This negative-going voltage is coupled by means of the feed-back resistor 69 to the grid of triode section 49b. The negative going voltage on the grid of triode section 4% causes that tube to become cut-off.

The reversal of condition of operation of the bistable circuit represented by conduction being cut off in triode section 49b and the commencement of conduction in triode section 49a makes counting in tube 10 possible. Such counting can only take place if the voltage on zero cathode 12a is raised to a point where the glow discharge investing the-zero cathode can be released.

Prior to the arrival of a count-initiating pulse and the ensuing reversal of condition of the bistable circuit, cathode 12a was in series with triode section 49b and glow-discharge current flowed from the first voltage source 21 to ground through cathodelZa. Current also flowed from the second source 43 through resistor 41 and triode section 4912 to ground. Because the value of resistor 41 is at least several times the combined value of resistors 46 and 57, the potential on cathode 12a is reduced to a very low value relative to the bias on'other cathodes of tube 10.

Now, however, after receipt of the counbiuitiating pulse and the accompanying reversal of condition of operation of the bistable circuit, triode section 49b is cut off and glow discharge current flows through -resistor 41 only. In these conditions, there is no flowof current through resistor-41 from the second source of voltage '43. The voltage at the lower end of resistor 41 remains established at the voltage of source 43, but the voltage at the upper end of resistor 41 becomes more positive than that of the second source by theIR drop caused by the flow therethrough of the .glow discharge current. In this fashion the voltage on-zero cathode 12a is raised sufiiciently that the glow. discharge may betaken from cathode 12a onto the guides -by the arrivalof a pulse to be counted.

The input circuit for pulses to be-c'ounted which includestriode amplifier'37is one which is preferred for use with pulses of certain shapes and repetition rates. In other circumstances, different circuits might -be preferred;-in fact, where counting tubes not-of the two-guide type, like tube 10 -shown,':are use'd, quite-a-diiferent inputcircuit would be used. However, in the'circuit disclosed, positive pulses or signals to be counted are applied at terminal 32 and are coupled to "the grid of triode37. They are inverted and amplified in the'triode. The flow discharge which, -as explained above, still 'invests the-zero cathode is transferred to the first guide 13. This transfer occurs because the count-initiating pulse has causedthe zero cathode to go to a-much higher positive value than that it had prior to'the'application-of the-count-initiating pulse.

The input pulse to triode 37,'having been amplified and inverted, drives the guide 13 in a negative'direction to a voltage considerably less than'that now on the-zero'cathode and the glow discharge moves to the guide13. As the glow discharge'current'fiows through resistor 25, condenser 27 becomes charged causing guide 13 to swing in a positive direction. Condenser 3'1,be causeit is connected inshunt with triode 37-and resistor 29'betweenthe guide 14 normally is in a charged condition. At the same time condenser 27 is becoming charged, condenser 31 is discharging through resistor 29 and the now conducting triode 37. The potential on guide 14 falls as condenser 31 discharges and at about the time the rising voltage on guide 13 is approximately equal to the falling voltage on guide 14, the input pulse being applied to the grid of triode 37 may terminate and cut ofi the flow of current through triode 37. For an instant, the glow discharge current then flows through resistors 25 and 29 to charge condenser 31. Because guide 14 is connected to the junction of resistors 25 and 29, the IR drop across resistor 25 provides a sutficient voltage difference between guides 13 and 14 to cause the glow discharge to transfer from guide 13 to the more negative guide 14. Upon transfer of the glow discharge to guide 14, the charging of condenser 31 continues at a more rapid rate until guide 14 becomes sutficiently more positive than the next adjacent main cathode to cause the glow discharge to transfer to that next main cathode.

The foregoing sequence of. switching is repeated for each pulseto be counted that arrives at terminal 32 until the glow discharge reaches and invests the cathode chosen to be final, cathode 12b in the drawing. The arrival of the next pulse to be counted causes the trans for of the glow discharge back to the zero cathode 12a.

A series of changes take place to cause this reset action. Prior to the arrival of the glow discharge at cathode 1213, that cathode is at substantially the value of second source 43 because it is not then conducting any of the glow discharge current. With the arrival of the glow discharge, the voltage developed across resistor 51 causes the cathode 12b to become more positive immediately. This positive swing is coupled to the grid of triode section 49a by way of resistor 47 and condenser 48, but no effect is had on triode section 49a because that section is already conducting.

Now, however, when the next pulse to be counted arrives at terminal 32, the .glow discharge commences to leave cathode 12b. As the glow leaves cathode 12b, it swings in a negative direction and this negative pulse 15 applied to the grid of triode section 49a causing that section to be cut off. The multivibrator action previously outlined causes triode section 4% to commence conduction. With conduction in section 49b, Zero cathode 12a, which is connected through the 20 thousand ohms of resistor 46 to the anode of triode section 4912, immediately is driven in a negative direction and the glow d1scharge transfers to cathode 12a.

Because cathode 12a is driven so far in a negatlve direction and held there as long as triode section 4% is conducting, further pulses arriving at terminal 32 are not counted because they are unable to drive-the guide 13 sufiiciently negative to remove the glow from cathode 12a. As explained hereinabove, only after a count-initiating pulse reverses the conduction in the bistable circuit, does cathode 12a reach a more positive value permitting removal of the glow discharge by the arrival of a pulse to be counted.

An output terminal 70 is shown connected to the anode of triode section 49b. Depending upon the polarity and the timing desired the output terminal may be connected where shown, to the anode of triode section 490 or to either the zero or final cathode of counting tube 10. With the illustrated connection, cessation of conduction in section 4%, which occurs upon receipt of a countinitiating pulse, causes the anode of section 4% to swing in a positive direction. The increased potential thus appearing at the anode of section 49b gives a positive output pulse. Terminal 70 may be used as a source of pulses to be counted or as a source of count-initiating pulses for further stages, depending upon the pulse requirements in cascaded counting tubes or in other circuit applications.

Thus, there is achieved a circuit which permits a counting tube which counts only after receipt of a countinitiating pulse and which counts only to a predetermined figure. By selection of the proper cathode as the final cathode any desired count may be had. Furthermore, no counting occurs until and unless a count-initiating pulse is first applied.

The invention should not be limited to the exact details shown and described. The embodiment disclosed is presently preferred, but other circuit components may be used in several areas. For example, the input circuit for pulses to be counted is replaceable by other types of circuits, particularly when counting tubes other than that shown are used. Similar substitutions in other areas are also feasible and are believed to be within the purview of the present invention. The invention should be limited only by the spirit and scope of the appended claims.

What is claimed is:

1. In combination a glow-discharge transfer counting tube having at least a zero cathode and a final cathode, means for applying pulses to be counted to said counting tube, a bistable circuit connected to said zero cathode and to said final cathode, said bistable circuit having a first condition of operation during which said zero cathode is held at a first potential and a second condition of operation at which said zero cathode is held at a second potential more positive than said first potential, means for applying a count-initiating pulse to said histable circuit to switch the same from said first to said second condition of operation, said pulses to be counted being of sufiicient amplitude to transfer said glow discharge during said second condition of operation and of insutficient amplitude to transfer said glow discharge during said first condition of operation, said counting tube being operative upon application of a predetermined number of said pulses to be counted to cause said glow discharge to be transferred from said final cathode, and means connecting said final cathode to said bistable circuit operative in response to the transfer of said discharge from said final cathode to return said bistable circuit to said first conditionof operation to transfer said glow discharge to said zero cathode to said bistable circuit final cathode being connected to said bistable circuit.

2. In combination, a multi-cathode glow-discharge transfer counting tube having at least a zero cathode and a final cathode, and a gate-reset circuit for said counting tube comprising, a bistable multivibrator having at least a grid and an anode, means connecting said anode to said zero cathode, said zero cathode assuming a first or a second potential depending upon the flow or lack of flow of current from said anode of said bistable multivibrator, said second potential being more positive than said first, means connecting said final cathode to said grid, means for applying a count-initiating pulse to said bistable multivibrator to cut off the flow of current from said anode and to set up the condition of operation at which said anode and said zero cathode assume said second potential, means for applying pulses to be counted to said counting tube, said pulses being of sufiicient amplitude to cause transfer of said glow discharge from said Zero cathode only when said zero cathode reaches at least said second potential, and means including the connection between said final cathode and said grid of said multivibrator for renewing the flow of current from said anode and the assumption by said zero cathode of said first potential upon the application to said counting tube of a predetermined number of pulses to be counted and consequent removal of said glow discharge from said final cathode.

3. In combination, a glow-discharge transfer counting tube having at least a zero cathode and a final cathode, and a gate-reset circuit for said counting tube comprising .a bistable multivibrator connected to said zero cathode, said zero cathode assuming either a first potential during one condition of operation of said multivibrator or a second potential higher than said first potential during the other condition of operation of said multivibrator, means for. applying a count-initiating pulse to said-multivibrator to switch .thesame from said one to said other condition of operation, means :forapplyingpulses to be counted to said'counting tube, said pulses causing transfer of said glow discharge from cathode to cathode in said counting tube, and means connecting said final cathode to said multivibrator-operative in response to the transfer of said glow discharge from said final cathode to cause said multivibrator-to resume said one condition of operation.

-4. in combination, a glow-discharge transfer counting tube having a plurality'of cathodes including zero cathode and a final cathode, and a gate-reset circuit for said tube comprising a bistable multivibrator including first and second triode sections, means for applying a countinitiating pulse to the grid of one of said triode sections, means connecting said zero cathode to the anode of said second triode section, means connecting said final cathode to the grid of said first triode section,.rneans for applying pulses to be counted to said counting tube, said counting tube being operative in response to a predetermined number of said pulses to cause transfer of said glow discharge from said final cathode and triggering of said bistable multivibrator to cut off said first triode section and to render said second triode section conducting, the potential of said zero cathode being decreased in response to conduction in said second triode section.

5. In combination, a glow-discharge transfer counting tube having an anode and a plurality of cathodes including at least a zero cathode and a final cathode, a source of potential connected to said anode, an input circuit for applying pulses to be counted to said counting tube to cause transfer of said glow discharge from cathode to cathode, a bistable multivibrator having a first and a second section, one of said sections being cut off and the other conducting at all times, said zero cathode being connected in series between said source of potential and said first section, the potential on said zero cathode being higher in a positive sense during conduction in said first section, an input circuit for said multivibrator, means for applying a count-initiating pulse to said multivibrator input circuit to terminate conduction in said second section and raise the potential on said zero cathode, and means connected to said final cathode and responsive to the transfer of glow discharge therefrom, said last-mentioned means also being connected to said multivibrator input circuit to initiate conduction in said second section to lower the potential on said zero cathode, said pulses to be counted being effective to cause transfer of glow discharge from said zero cathode only when said potential thereon is raised by conduction in said first section.

6. A pulse counting circuit comprising, in combination, a glow-discharge transfer tube having an anode and a plurality of cathodes and responsive to pulses applied thereto to advance the discharge step by step to successive ones of said cathodes, all of said cathodes being connected together except two designated zero and final cathodes, means for applying input pulses to be counted to said counting tube, and a gate-reset circuit operable in response to an enabling pulse to initiate counting from said zero cathode and to terminate counting action of said counter tube in response to the application of the last of a predetermined number of input pulses, said gate-reset circuit inciuding a bistable circuit having first and second stable conditions of conduction and circuit means connecting said bistable circuit to said zero and final cathodes, said gate-reset circuit being operative upon being switched from its first to its second stable condition in response to an enabling pulse to increase the potential on said zero cathode, and operative upon being switched from its second to its first stable condition in response only to an input pulse applied to said counting tube following the transfer of the discharge to said final cathode to increase the potential on said final cathode and to decrease the potential on said zero cathode thereby to transfer the discharge to said zero cathode.

7. A,pulse counting circuit comprising, in combination, a glow-discharge .transfertubehaving an anode and a plurality of cathodes .and responsive to .pulses .applied thereto to advance the discharge step by step to .succes sive ones of said cathodes, all of said. cathodes being connected together except two designated zero and final cathodes, means for applying input pulses to be counted to said counting tube, and a gate-reset circuit including a multivibrator having .first and second stable conditions of .conduction and includinga pair of electron tubes each having at least an anode and a control grid, a resistor network connecting the anodes of said electron tubes to said zero and said final cathodes, and a pulse-coupling connection from said final cathode to the grid of one of said electron tubes, said gate-reset circuit being operative upon switching of said multivibrator from its first to its second stable condition in response to an enabling pulse applied to one of said grids to increase the potential on said zero cathode to a level sufiicient to cause transfer of the discharge therefrom by an input pulse applied to said tube, and operative upon switching of said multivibrator from its second to'its first stable condition in response to the input pulse next following the pulse causing transfer of the discharge to said final cathode to increase the potential on said final cathode and decrease the potential on said zero cathode thereby to transfer the discharge to said zero cathode where it is retained until the application of another enabling pulse.

8. A pulse counting circuit comprising, in combination, a glow-discharge transfer counting tube having a plurality of cathodes all connected together except two designated zero and final cathodes, a like plurality of connected first guide electrodes, a like plurality of connected second guide electrodes, and an anode common to said cathodes and guideelectrodes, means including a first voltage source connected to said common anode for establishing a glow-discharge at one of said cathodes, means for applying input pulses to be counted to said guide electrodes, and a gate reset circuit to initiate counting from said zero cathode only in response to an enabling'pulse and to terminate counting action in said counting tube after application of a predetermined number of input pulses, said gate-reset circuit including a multivibrator having first and second stable conditions of conduction and means connecting said multivibrator to said zero and final cathodes, said connecting means and said multivibrator being arranged whereby said multivibrator is switchable from its first to its second stable condition only in response to an enabling pulse applied thereto and switchable from its second to'its first stable condition only in response to an input pulse applied to said guide electrodes following the transfer of the discharge to said final cathode.

9. A pulse counting circuit comprising, in combination, a glow-discharge transfer counting tube having a plurality of cathodes all connected together except two designated zero and final cathodes, a like plurality of connected first guide electrodes, a like plurality of connected second guide electrodes, and an anode common to said cathodes and guide electrodes, means including a first voltage source connected to said common anode for establishing a glow discharge at one of said cathodes, means for applying input pulses to be counted to said guide electrodes, and a gate-reset circuit to initiate counting from said zero cathode only in response to an enabling pulse and to terminate counting action after application of a predetermined number of input pulses, said gate-reset circuit comprising a multivibrator having first and second stable conditions and including first and second electron tubes each having at least an anode, a cathode and a control grid, a second voltage source, a network of resistors in circuit with said second voltage source and connecting the anodes of said first and'second electron tubes to said final cathode and said zero cathode of said counting tube, and a pulse-coupling connection from said final cathode to the grid of said second electron tube, said multivibrator and the aforesaid circuitry being arranged whereby said multivibrator is switchable from its first to its second stable condition only in response to an enabling pulse applied to one of said grids and switchable from its second to its first stable condition only in response to an input pulse applied to said guide electrodes following the transfer of the discharge to said final electrode.

10. A pulse counting circuit comprising, in combination, a glow-discharge transfer tube having an anode and a plurality of cathodes and responsive to pulses applied thereto to advance the discharge step by step to successive ones of said cathodes, all of said cathodes being connected together except two designated zero and final cathodes, means for applying input pulses to be counted to said counting tube, and a gate-reset circuit comprising a multivibrator having first and second stable conditions of conduction connected to said zero cathode, and means including a voltage source in circuit with said multivibrator for applying a first potential to said References Cited in the file of this patent UNITED STATES PATENTS 2,648,831 Vroorn Aug. 11, 1953 2,664,555 Thomas Dec. 29, 1953 2,690,525 Koehler Sept. 28, 1954 2,693,552 Steinberg Nov. 2, 1954 2,714,179 Thomas et al. July 26, 1955 2,740,921 Hough et al. Apr. 31, 1956 2,774,534 Dunn Dec. 18, 1956 

